A gas generator for immediately deploying an airbag has been conventionally built in various airbag modules in order to protect an occupant from an impact caused by an automobile crash. The gas generator immediately generates a large amount of high-temperature gas based on a crash detection signal transmitted from a crash sensor at the time of an automobile crash.
For the gas generator, an igniter which has a system for igniting an inner ignition material when receiving the crash detection signal from the crash sensor and converts an electric signal to ignition energy, gas generants for receiving the ignition energy from the igniter to generate a large amount of gas, a metallic cylindrical housing for housing the igniter and the gas generants therein, and a holder for fixing the igniter to the housing are typically cited as minimum components required. Additionally, a filter may be employed which absorbs a large amount of heat and combustion particles generated by combust ion of the gas generants as the need arises.
Moreover, a main part of the igniter generally includes a plastic material composed of a thermoplastic resin and the like, and is fixed to the metallic holder by a caulking method.
As a method for fixing the holder to the metallic housing, welding and the like are known (see the Patent Document 1).
Additionally, as a method for fixing a sealing plate of the gas generator to the housing, caulking is known (see the Patent Document 2). Particularly, in this method, the sealing plate and the housing composed of the same kind of steel materials such as a high-tension plate are subjected to caulking and striking to be fixed to each other.
Additionally, a gas generator is known in which a part of an inner cylindrical member provided in the housing is caulked so that an igniter assembly (igniter and collar) is fixed to the inner cylindrical member (see the Patent Document 3).
Additionally, a gas generator is known in which a part of an elongated cylindrical housing is diameter-reduction processed in relation to a lid member with a stage so that the lid member is fixed to the housing (see the Patent Document 4).    Patent Document 1: Japanese Unexamined Patent Publication No. 2003-112597    Patent Document 2: U.S. Pat. No. 3,475,392    Patent Document 3: Japanese Unexamined Patent Publication No. 2004-293835    Patent Document 4: International Publication No. WO01/074632